<?php

class Interval
{
    function __construct(
        $lowerBound,
        $upperBound,
        bool $lowerClosed = true,
        bool $upperClosed = false
    ) {
        $this->lowerBound = $lowerBound;
        $this->upperBound = $upperBound;
        $this->lowerClosed = $lowerClosed;
        $this->upperClosed = $upperClosed;
    }
    function __toString(): string
    {
        return ($this->lowerClosed ? "[" : "(") .
            $this->lowerBound .
            ", " .
            $this->upperBound .
            ($this->upperClosed ? "]" : ")");
    }
    function contains($value)
    {
        return ($this->lowerClosed
            ? $this->lowerBound <= $value
            : $this->lowerBound < $value) &&
            ($this->upperClosed
                ? $value <= $this->upperBound
                : $value < $this->upperBound);
    }
    // private member
    //- variables
    // upper/lower bounds for the interval
    private $lowerBound;
    private $upperBound;
    // on true the bound is in the interval, otherwise not
    private $lowerClosed;
    private $upperClosed;
}
// data type for an age class
class AgeGroup
{
    // public member
    // - functions
    function __construct(string $label, Interval $years)
    {
        $this->label = $label;
        $this->years = $years;
    }
    function __toString(): string
    {
        return $this->label . " " . $this->years;
    }
    function years()
    {
        return $this->years;
    }
    /** factory method for AgeGroup-s
     *
     * @param [string] $label string denoting the AgeGroup
     * @param [type] $year the year to reference the AgeGroup to
     * @return AgeGroup interval of years of the age group
     */
    public static function create(string $label, ?int $year = null)
    {
        // input sanitation
        $year =
            filterPosInt($year) ?? filterPosInt((new DateTime())->format("Y"));

        $lowerYear = null;
        $upperYear = null;

        // Matching against the different age class formats
        // - ..Ux
        // - Jg.x-y

        // Case Ux
        $akUmatchString = "/(.*)U([0-9]+)(.*)/";

        $matches = [];

        preg_match($akUmatchString, $label, $matches);
        // The found match should cover the whole string. Otherwise it isn't applicable.
        if ($matches[0] == $label) {
            // The x in Ux should be a positive integer.
            $ageLimit = filterPosInt($matches[2]);
            if ($ageLimit) {
                $lowerYear = $year - $ageLimit + 1;
                // lowering the lower bound according to the modifiers
                if ($matches[3] == "") {
                    $upperYear = $year - $ageLimit + 2;
                } elseif ($matches[3] == "-") {
                    $upperYear = $year - $ageLimit + 3;
                } elseif ($matches[3] == "--") {
                    $upperYear = $year - $ageLimit + 4;
                } elseif (
                    in_array($matches[1], [
                        "<=",
                        "&le;",
                        "&#x2264;",
                        "&#8804;",
                        "≤",
                    ])
                ) {
                    $upperYear = $year;
                }
                return new AgeGroup(
                    $label,
                    new Interval($lowerYear, $upperYear, true, true)
                );
            }
        }

        // Case Jg.x-y
        $akUmatchString = "/Jg\.(.*)\-{1,2}(.*)/";

        $matches = [];

        preg_match($akUmatchString, $label, $matches);
        // The found match should cover the whole string. Otherwise it isn't applicable.

        if ($matches[0] == $label) {
            $lowerYear = filterPosInt($matches[1]);
            $upperYear = filterPosInt($matches[2]);

            return new AgeGroup(
                $label,
                new Interval($lowerYear, $upperYear, true, true)
            );
        }

        return new AgeGroup(
            $label,
            new Interval($lowerYear, $upperYear, true, true)
        );
    }

    // private member
    // - functions
    // - variables
    private $label;
    private $years;
}